1. Field of the Invention
This invention relates to telephone networks or systems and concerns a system suitable for the immediate identification of the identity number of a calling station A on a called station B which may be connected through any number of intermediate automatic exchanges in a telephone network within a country or political area and even on a worldwide basis if the necessary agreements between countries have been previously made.
2. Description of the Background
Ever since the introduction of automatic telephone exchanges, there have been repeated attempts to find a simple and fast method, enabling one to detect the identity number of a calling station A at a remotely located called station B, an objective being to eliminate, or at least reduce, the possibility of malicious anonymous calls, which sometimes, as in the case of bomb threats or other terrorist activities, is not only desirable but a real need.
The present invention covers and claims improvements made by the corporation, which have allowed it to develop a complete system and complementary hardware, applicable to any kind and in any number, and which includes the necessary programming or software, as well as the basic characteristics of the essential circuit blocks of the complementary hardware. The result is a call tracing system and identification detector which can immediately indicate, upon receiving a telephone call at a called station, not only the identification number of the caller but also the type of subscriber, for example, regular, public telephone or other (given by the category) and the location of the calling station, given by the area code or the country code in the case of international calls.
Many prior art arrangements have been proposed to identify calling stations connected with called stations and attendant positions through automatic exchanges. These systems are based on several different principles and generally they are only applicable to special cases, as they introduce additional complications in the network and the expense is such that it hardly allows the development of a product within the reach of the ordinary telephone subscriber. Usually, they are based on one or more of the following methods:
Introduction of strange additional signaling in the telephone network.
Operation of a switch or electrical connection to start the identification process.
Use of alternative routes to trace the calling station.
Use of additional devices at the local exchange, which very often is not possible for the simple reason of the space available, independently of the costs that might be incurred.
Usually, they entail a risk of interference with the regular telephone exchange control signaling.
As a general rule, an ideal system for identifying calling stations should have the following characteristics:
It should not require any modifications at the calling station.
It should not be detectable by the calling party to avoid alerting it that it is being identified.
It should allow, if desired, immediate identification of the calling station by the single fact of receiving a call at the called station, without even lifting the receiver.
It should preferably not introduce any strange signaling in the telephone network, that is, it should not use any other signaling than that of the telephone network itself, to avoid any possibility of interfering with its regular operation.
It should not require the installation of any additional devices in the switching exchanges of the telephone system.
The hardware to be used at the called station should occupy minimum space and even offer the possibility of being incorporated in the subscriber set as an integral part of it.
It should allow the development of a type of hardware which requires the previous knowledge of the called subscriber for it to be installed, in order to comply with any existing regulations on the Right of Privacy.
As a complement to the previous condition, if connected without the knowledge of the private subscriber, it should not operate nor interfere with the operation of the telephone network.
It should not be possible to install it without the cooperation and knowledge of the telephone operating company, to ensure not only full compatibility with the regular operation of the network but also as an additional guarantee for private subscribers.
It should allow commercial production at a sufficiently low price for it to be within the reach of any subscriber and not only of official institutions or major corporations.
This invention seeks to provide a system which for the first time fulfills some or all of these conditions.